Rubber dam clamp

ABSTRACT

The rubber dam clamp is made of fiber-reinforced plastic. The dam clamp has a pair of gripping claws that are adapted to engage a tooth neck. A resilient bridge connects the gripping claws. A pair of open sockets are defined in an inside of the gripping claws between the bridge and the gripping claws. The sockets are adapted to receive the points of a rubber dam clamp forceps so that the dam clamp may be opened without the risk of the forceps being caught in the socket when the dam clamp is released and the forceps is to be removed therefrom.

TECHNICAL FIELD

The invention relates to a rubber dam clamp, that is to say a clampwhich is used by dentists as an aid for securing a so-called rubber damsheet on the teeth and which for this purpose has a pair of grippingclaws, intended to engage against a tooth neck, and a resilient bridgewhich connects the gripping claws.

BACKGROUND TO THE INVENTION

The purpose of the rubber dam sheet is to isolate the field of operationon the teeth from saliva, blood and respiratory air, but also to preventchemicals, filling material etc. from coming into contact with mucousmembranes and the throat. Rubber dams have been used at least since the1920s, and most of the associated aids have changed little since then.The rubber dam clamps which are used to secure the sheet on the teethhave hitherto been made of metal and are available in a large number ofsizes and shapes. They consist of a single or double resilient bridgeand of gripping claws which will engage against the tooth neck and whichfor this purpose are shaped in accordance with the anatomy of the toothnecks. The clamps are stiff and must be applied and removed usingspecial forceps, with points, which are fitted into forceps sockets inthe form of holes in the area of the gripping claws.

The rubber dam clamps made of metal have a number of disadvantages. Inaddition to the fact that they are relatively expensive and to a largeextent absorb X-radiation, it should also be noted that considerableforce is required when applying and removing them, they are felt to beuncomfortable by the patients ("iron grip"), and the metal edges cause agreater or lesser amount of damage to the tooth necks. When the clampsare stretched out to a large degree, the fixture holes for the forcepsare often positioned obliquely in relation to the jaws of the forceps,with the result that it can be extremely difficult to remove the forcepsand even more difficult to stick the points of the forceps into theholes when the clamp is to be removed.

BRIEF DISCLOSURE OF THE INVENTION

The object of the invention is to eliminate the abovementioneddisadvantages and at the same time to offer further advantages, and thiscan be achieved by virtue of the fact that the invention ischaracterized by what is stated in the patent claims which follow.

It is expedient that the basic shape of the rubber dam clamp accordingto the invention should correspond to that of conventional rubber damclamps made of metal so that it will be compatible with existing rubberdam forceps and other aids. However, the use of fibre-reinforcedplastic, which is proposed preferably as the material for the rubber damclamps in place of metal, affords considerable possibilities forvariations in the design. Thus, the clamp can and should be givenvarying material thickness in different parts of the clamp in orderthereby to obtain an optimal combination of spring power, manageability,gripping capacity etc. To this end, the bridge is preferably given agreater material thickness than, for example, the claws.

By means of a suitable material distribution it is also possible, inaccordance with a preferred embodiment, to make the clamp more elongatethan conventional rubber dam clamps made of metal, as a result of whichthe rubber dam sheet can be better held away distally from the tooth, sothat the dentist has more room for the instruments.

In addition to closed sockets in the form of holes for the rubber damforceps, or as an alternative to these, open sockets for the forceps arearranged, according to the invention, on the inner side of transitionareas between the bridge and each gripping claw. These open sockets forthe forceps can comprise parts of the said transition areas, the surfaceagainst which the forceps are pressed in the respective forceps socketextending in a plane which is essentially at right angles with respectto a base plane, which is defined by the inner edge of the grippingclaws. More specifically, these open sockets for the forceps areexpediently given the form of groove-shaped recesses in the inner sides,facing each other, of the transition areas. According to a preferredembodiment these recesses extend in a direction essentially at rightangles with respect to the base plane. By using these open sockets forthe forceps, there is never any risk, for the dentist, of the forcepsbecoming stuck.

According to another possible embodiment, the open sockets for theforceps consist of essentially T-shaped recesses, with the horizontalpart of the forceps socket being parallel to and directed towards thesaid base plane, and the forceps intended for use with these recesseshaving points which are shaped so as to fit into these recesses.

The technique for producing the rubber dam clamp according to theinvention also involves such low production costs that the rubber damclamp can be used as a throw-away article. It is also possible for thedentist himself, using a file or a rotary grinding tool, for example asmall grinding wheel in a dental drill machine, to cut out a suitableshape for the inner edge of the gripping claws, so that this edge isadapted to the tooth neck in question. In this way it is possible ineach situation to achieve a very good contact with the tooth, and at thesame time the number of shapes and sizes of the rubber dam clamps keptin store can be reduced.

Another advantage of rubber dam clamps having a plastic matrix is thatthe rubber dam sheet can be more easily secured to the clamp,expediently by gluing or welding.

Plastics which can be used as the material for the rubber dam clampsaccording to the invention include a number of thermoplastics. Somepolyamide plastics are especially suitable, and in particular nylon-12.Acetal plastic (polymerized formaldehyde, POM) can also be used. Acopolymer thereof with a small quantity of ethylene oxide or dioxane isalso possible.

Among suitable fibres there may be mentioned, in the first instance,glass fibres of micro size, which is here understood to mean lengths ofless than one millimetre. The glass fibres can preferably have a lengthof the order of magnitude of "a tenth of a millimetre or so", which canalso be expressed by saying that most of the glass fibres (of the totalvolume or mass of the fibres) will have a length within the range from0.05 to 0.5 mm. The plastic should expediently contain 20-60% by weightof glass fibres, preferably 30-50% by weight. Among other possiblefibres which can be used as a reinforcement for the material, carbonfibres may be mentioned. If carbon fibres are used instead of glassfibres, a smaller quantity can give the same reinforcing effect. Mineralfibres, fibres of organic material etc. are also possible, in principle,as the ingredient for reinforcing the plastic matrix.

Further characteristics and aspects of the invention will emerge fromthe following patent claims and from the description, given below, of apossible embodiment of a rubber dam clamp made of plastic according tothe invention.

BRIEF DESCRIPTION OF THE FIGURES

In the following description of a possible embodiment, reference will bemade to the attached drawing, in which:

FIG. 1 shows, on an enlarged scale, a perspective view of a rubber damclamp made of plastic according to the invention,

FIG. 2 shows the same rubber dam clamp from one side,

FIG. 3 shows the rubber dam clamp from above, and

FIG. 4 shows a part of the rubber dam clamp in a section through IV--IVin FIG. 3, on an even larger scale.

DESCRIPTION OF A PREFERRED EMBODIMENT

The rubber dam clamp shown in the figures of the drawing is produced,according to the preferred embodiment, by injection moulding of nylon-12containing 40% by weight of glass fibres, with most of the fibres beingin the length range from 0.05 to 0.5 mm. The clamp consists of aresilient bridge 1, a pair of claws 2, 3, the inner bevelled edges 4 ofwhich form a grip 5, and, between the resilient bridge 1 and the claws2, 3, a pair of transition areas 6, 7. The latter are more elongate thancorresponding parts of conventional rubber dam clamps made of metal andcan be described as legs protruding from the bridge 1, which legs endwith the inwardly directed gripping claws 2, 3, the inner edge 4 ofwhich defines a base plane 10. Despite the considerable length of thetransition areas/legs 6, 7, the necessary spring force can betransmitted from the bridge 1 to the gripping claws 2, 3 by virtue ofthe fact that the transition areas 6, 7 are given an apposite materialthickness adapted to the moments which may arise during the use of therubber dam clamp. The bridge 1 itself is also normally given arelatively large wall thickness in order to provide a correspondingspring force, while the gripping claws 2, 3 are designed narrowingtowards the edge 4 so that the desired gripping effect against the toothneck is obtained.

In each of the transition areas 6, 7 there is an upper part 11 whichadjoins the bridge 1. On inner side 20 of these two opposite upper parts11 there is a recess 12 which is in the form of a groove which isessentially vertical in relation to the base plane 10, when the latteris horizontal. The design of such a groove 12 is shown in FIG. 4.However, the grooves can have another direction or design, especially ifa rubber dam forceps other than the conventional one is to be applied.The two grooves 12 function as open sockets for the points of a rubberdam clamp forceps, which is applied against the inner wall 13 in therespective groove 12. This inner wall 13 extends in the verticaldirection, that is to say in a direction at right angles with respect tothe base plane 10.

Between the two open forceps sockets 12 and the gripping claws 2, 3there is also a pair of closed forceps sockets of conventional design inthe form of through-holes 14.

It is claimed:
 1. Rubber dam clamp having a pair of gripping claws (2,3), intended to engage against a tooth neck, and a resilient bridge (1)which connects the gripping claws, each gripping claw having a thicknessand an inner side disposed between the resilient bridge and the grippingclaws so that each inner side is facing one another, each inner sidehaving an open socket defined therein adapted to receive points of arubber dam clamp forceps, the open sockets facing towards one another,the rubber dam clamp being made of a fiber reinforced material, theresilient bridge having a thickness that is greater than the thicknessof the gripping claws, the sockets having an inner surface facing oneanother so that the sockets are partially defined by the inner surfacesand bottom surfaces.
 2. Rubber dam clamp according to claim 1 wherein asubstantially round opening is formed by the gripping claws when thegripping claws are adjacent one another.
 3. Rubber dam clamp having apair of gripping claws having a thickness, intended to engage against atooth neck, and a resilient bridge which connects the gripping claws,each gripping claw having an inner side disposed between the resilientbridge and the gripping claws so that each inner side is facing oneanother, each inner side having an open socket defined therein adaptedto receive points of a rubber dam clamp forceps, the open sockets facingtowards one another, the rubber dam clamp being made of a fiberreinforced material, the resilient bridge having a thickness that isgreater than the thickness of the gripping claws, the open forcepssockets (12) are defined in upper parts (11) of transition areas (6, 7),the inner surface (13) against which the forceps point is pressed intothe respective socket (12) extending in a plane which is essentially atright angles with respect to a base plane (10), which is defined by theinner edge (4) of the gripping claws.
 4. Rubber dam clamp according toclaim 3, characterized in that the said open forceps sockets (12) areformed by groove-shaped recesses in the inner sides, facing each other,of the transition areas, which recesses extend at least partially in adirection essentially at right angles with respect to the base plane(10).
 5. Rubber dam clamp according to claim 4, wherein each socket isdefined by an inner wall and a base plane, the inner wall isperpendicular to the base plane.
 6. Rubber dam clamp according to claim3, characterized in that the open forceps sockets (12) are arrangedbetween the bridge (1) and closed forceps sockets (14), in the form ofthrough-holes in the two gripping claims (2, 3).
 7. Rubber dam clampaccording to claim 3, wherein the rubber dam clamp comprises a polyamideplastic.
 8. Rubber dam clamp according to claim 7, wherein the polyamideplastic is acetal.
 9. Rubber dam clamp according to claim 7 wherein theplastic contains 30-50% by weight of glass fibres.
 10. Rubber dam clampaccording to claim 7, characterized in that the plastic contains 20-60%by weight of fibres.
 11. Rubber dam clamp according to claim 3,characterized in that the fiber reinforced material consists of glassfibres.
 12. Rubber dam clamp according to claim 11 characterized in thatmost of the fiber reinforced material comprises fibres that have alength of between 0.05 and 0.5 mm.
 13. Rubber dam clamp according toclaim 12 wherein the fibres consist of carbon fibres.